1. Technical Field
The present invention relates to a printing apparatus including printing units capable of executing printing on a print surface of a printing medium and allowing the printing units to execute the printing in parallel.
2. Related Art
There is known a printing apparatus including a plurality of printing units capable of executing printing on a print surface of a printing medium and allowing the printing units to execute the printing in parallel. For example, there is a printing apparatus which includes a plurality of printing units arranged in a vertical direction and a unit discharging a printing medium discharged from the printing units to a common sheet receiver (for example, see JP-A-8-211673). The printing apparatus is capable of causing the plurality of printing units to simultaneously print a plurality of printing media in parallel when continuously printing the plurality of printing media. According to the known technique, it is possible to improve throughput of the printing apparatus.
The printing apparatus including a turnover unit turning over the front and rear surfaces of the printing medium is capable of executing printing on the front and rear surface of the printing medium. Therefore, by disposing the turnover unit in the printing apparatus including the plurality of printing units capable of executing the printing on the print surface of the printing medium and allowing the printing units to execute the printing in parallel, the printing apparatus can realize the printing on both sides of the printing medium at a high speed. While one printing unit executes the printing on the rear surface of the printing medium after the printing on the front surface of the printing medium, another printing unit can execute the printing on the front surface of the next printing medium in parallel. Therefore, the printing can be executed on both surfaces of the printing medium more efficiently.
However, the length of a transport path of the printing medium between the printing units is different depending on how the printing unit used when executing front surface printing and the printing unit used when executing rear surface printing are selected. Completing the printing on both surfaces of the printing medium tends to be more time-consuming, as the transport path of the printing medium between the printing units becomes longer. Therefore, in order to execute the printing on both surfaces of the plurality of printing media simultaneously, a bottleneck may occur in the printing medium transported along the longest path between the printing units. Therefore, the improvement in throughput may not be achieved.